Expression of genes of Trichoderma harzianum in response to the presence of cadmium in the substrate

Abstract

Trichoderma harzianum is a very important fungus for the reduction of the amount of heavy metals resulting from agricultural and industrial activities. This filamentous fungus has been shown to be tolerant towards several heavy metals (e.g. Cd, Pb, Zn, Ni and Mn), but the mechanism underlying this tolerance is not entirely understood. In this study, we confirmed the ability of T. harzianum to grow in the presence of cadmium and observed a significant stimulation of its growth in the presence of mercury. A molecular approach to investigate the cadmium tolerance mechanisms was carried out by the application of the suppression subtractive hybridisation (SSH) technique. To this end, we have used a particular strategy to discriminate cadmium-induced differentially expressed genes from those generally expressed upon heavy metal treatment. Several genes (109) were found to be overexpressed in the presence of cadmium, confirming the dramatic metabolic modification underlying the metal stress response of the fungus.

Keywords:

• filamentous fungi
• cadmium tolerance
• heavy metals
• SSH technique.

Acknowledgements

This research was supported by grants of Profs. G. Petrone and S.O. Cacciola provided by the University of Catania (PRA 2007, 2008) and by the Ministero dell’Istruzione, dell’Università e della Ricerca (MIUR, Italy; PRIN 2008). Dr V. Sanzaro was sponsored by a grant from Faculty of Pharmacy of the University of Catania. The Authors wish to thank Mrs Ann Davies Muni for the English revision of the text.